SA-15 D4 Rev 2 - Sundown Audio 15" Dual 4-Ohm SA Series Chrome Subwoofer SA-15 D4 Rev 2 - Sundown Audio 15" 600W Dual 4-Ohm SA Series Subwoofer RMS: 600W Thick black anodized aluminum voice coil formers for maximum strength and heat dissipation 4layer copper high temperature voice coil windings with 45mm winding length Mounting Depth: 7 1/2"